Apparatus for grinding wood pulp



7 :Sheets-Sheet- 1 J. J. WRREN APPARATUS NR GRINDING 'OOD PULP ried oct. 14, 1922' Illllll ll'lllll Aug. 19 1924.

:1l-JESSE] Aug. 19'. 1924. 1,505,757

J. J. WARREN APPARATUS FOR GR'INDING WOOD PULP nl ed oct. 14,V 1922 '7 sheets-sheet 2 INVENTOR .L 8MM Y A'. ATTORNEY:

0 au J uim m n IN VEN TOR f MMU/4 YLQATTORMEYS Aug. 19 1924.

J. J. WARREN APPARATUS FOR GRINDING woon PULP Filed Oct. 14 1922 7 Sheets-Sheet 5 Aug. 19, 1924.

. J. J. WARREN APPARATUS Fon GRINMNG woon PULP Filed Oct. 14, 1922 '7 Sheets-Sheet 4 INVENTOR E5 L'. AToRNE-Ys Sheets-Sheet 5 Aug. 19 1924.

J. J. WARREN APPARATUS FOR GRINDING WOOD PUL? Filed Doi. 14, 1922 INVENTOR ATTORNEYS Wild@ Qi@ 1,505,757 J. J. WARREN APFRATUS FOR GBINDEEG NUDI) PIJL? Fle Gai. l- 1922 7 Shees-Shee E Aug. 19 1924.,

mi@ SW,

g Patented- Aug. i9, i924.

vUNITED sraras ten-rca r ori-ica JOHN J'. WARREN, 0F BROWNVILEE, NEW YORK.

APPARATUS FOB GRINDING WOOD FULP.

Application led Dctober 1 4, 1922. Serial No. 594,501.

new 'and useful vImprovements in Apparatus Y for Grinding Wood Pulp; and I do hereby declare the followin `to be a full, c ear, and exact description o the invention, such as will enable other skilled in the art to` which it appertains to make and use the same.

This'invention relates to the grinding of wood into the so-called mechanical pulp used in the manufacture of newsprint and other cheap papers, and morel articularly to improvements in grinders o the maga` zine type, and methods of grinding wood therein. The presentapplication is a continuation in'part of my copending app'ication, Serial No. Ll01 ,874, filed August i', 1920, now Patent No. 1,465,069, August M, 1923.

The most common type of `mechanical wood pulp grinder in use today is that in which a plurality of pockets are radially disposed about a grindstone. Wood is periodically charged into these pockets and ground by being forced under pressure against. a rapidly rotating grindstone. Such grinders possess the advantages of a positive and regulated feed, but the disadvantages of a feed which is not continuous, which requires constant watching lest the pocket become empty Vand the stone race, in which the power consumption is not constant and in which the grinding is being continually interrupted. The time lost in frequent tiling of the pockets and the costof labor to operate such types of machines is not inconsiderable, andthe production is not constant because the amount of pulp ground varies while the supply of grinding water does not. But more serious than this is the continual interruption of the grinding action. During steady grinding the ground pulp in the pit piles up along the emerging tace of the stone and cleans it. As soon as the grinding is interrupted, as by the emptying of a pocket, this condition is disturbed, and a considerable increase in power is required t0 start the grinding with a new pocket and get it back to normal again. With al pocket grinder no sooner is this normal reached than another pocket empties and conditions are again interfered withand so on.

The magazine type of grinder avoids these disadvantages in a measure. In this grinder the wood is charged into a tall magazine positioned vertically above and adjacent to the grindstone, the capacit 0f this magazine being many times that o the pockets ofthe radial pocket rinder. Hence the necessity for constant y refilling the pockets is eliminated, and the continual interruption and disturbance of the'grinding action might also be eliminated could a continuous feed be attained. Attempts have been made to rely upon the weight of the wood itself in the magazine to exert the necessary grinding pressure for a continuous feed, but these attempts have not been successful because the weight of an average column of pulp-wood twenty-six feet high and about ten square feet in'cross section is approximately 6500 pounds, whereas a pressure of approximately 64,000 pounds ls required when a grindstone of appropriate size is consuming maximum horsepower. It is therefore clear that to obtain the requisite pressure by gravity alone would necessitate the bui'ding of a magazine of impracticable height. To avoid this various methods and means have been proposed for supplementing the insufficiency or gravity.

It has been proposed to em loy a series of reciprocating catcher mem ers moving alternately up and down along the sides of the magazine and contacting with the ends of the logs to pull the column of Wood downward in contact with the rindstone, but the mechanism of this type oes not possess strength suiicient to accomplish this end and overcome the arching tendency of the logs, nor can it compensate for the loose and irregularrapacking of the logs due to the variation 1n size and shape. Furthermore, the Y:iced is not continuous and grinding must stop during the retractile movement of the catcher members to their starting position, which means that the grinding is interrupted and the power consumption far from constant.

Anotl'ier proposed grinder comprises a pair of alternatel acting horizontal pressure feet which orce the Wood from the magazine against the sides of the grindstone. Et is not ossible to attain a constant feed with a device of this type due largely llO to the inequalities of the sizeof the logs, and to the fact that the wood does not a1- was fall from the magazine and completely an quickly fill the space between the grin stone and the retractin pressure-foot. This means that the feed 1s not. constant, that the grinding is continually interrupted, and the power consumption of the stone must vary over a wide range.

v As a still further improvement in the gravity feed ma azine inder it has been roposed to emp oy en ess chains moving down the inner side walls of the grinder with the Awood column. These chains reduce the friction between the wood andthe .magazine walls, thus increasing the effective gravity ressure, and they also add somewhat to t e total pressure. -But these chains have not solved the problem because they havebeen designed, not as the primary pressure applymg means, but merely as vauxiliaries to gravity. Various other arrangements of feed chains 'have also been proposed but these have been either too short to gri the wood sufficiently, have been designe to contact with the ends of the logs and not with their sides, or have turned about sprockets mounted so far above the grindstone that the `wood has counter-- arched above the stone and interfered with the continuous and smooth operation ofthe grinder. p It is, therefore, first of al1,`an object of this invention to provide a magazine grinder with a feed which is positive and continuous. This is attained by the provisin of opposing, continuously operating -woodgripping feeding means actin along substantially the entire length o those sides of the ma azine which, if extended, would intersect t e cutting face of the stone, and operating up to a point so closely adjacent the grindstone that no counterarching or jamming of the wood can occur. The magazine being of substantial hei ht relative to the diameter of the stone, t e wood-gris ping feeding means act along a column of wood of suiicient height to ive the necessary purchase. Preferably employ continuous, motor-driven chains which pass" downward along the inner face of the magazine for substantiallyits entire length, and are driven by sprockets situated so close to the grindstone that no binding or counterarching of the wood occurs between the s rockets and the stone. These chains grip t e wood at itsside by means of spurs which dig into the wood, and slowly press the wood as a continuous compact column against the rotating stone. The construction of'tliese chains and the location of the spurs are important and forni a part of the invention.

But even with a continuous feed the power consumption of the grinder would not necesactin asomar saril bev constant, as' the hardness of the woo and the tightness of the packing will v ary from point to point along the magazine. A constant power consumption is atly to be desired, not only because over' oad may 'burn out the motor, and because power is paid for on the basis of the peak load, but also because a more uniform pulp results. It is therefore a further object of this invention to make the rateJof feed variable, responsive tothe-power consumption of the stone, so that an increase in the power is immediatel followed by. a slowin down of the feed ciiains, and vice versa. du this way by maintaining the power consumption not disturbed and the grinder can work at maximum eicienc from weekmto week. This object is attained by the provision of means which control current to the feed chain motor, so that it bears a predetermined relation to the power consumption of the grindstone driving unit.

As the stone wears away and becomes smaller the space between it and the foot of the magazine becomesv correspondingly larger, if this condition were not remedied small pieces of wood would be carried through between the bottom of the magazine and the grindstone and not be ground. Moreover the distance between the oint where the chains leave the wood an the stone would increase. It is a further object of this invention to avoid these difficulties. This is done by making the magazine itself vertically adjustable, so that .it can be lowered as the rindstone wears away the feed chains am? the sprockets moving with it, and thus maintain a constant distance between the bottoml of the magazine and the grindstone and between the oint where' the chains leave the wood an the grindstone.

It is a further object of this invention to provide suitable means for supporting and stiening the lower end cf the magazine as well as to provide a suitable beam on lthe grinder end to counteract the great ressure exerted against this part by the orce of the grinding action. Means for counterthis excessive ressure have never been eretofore provi ed for in any wood pulp grinder.

It is also an object of the present invention to provide means for delivering the wood to the feed chains in .the form of a compact mass when so desired, and in fact to make the best continuous feed magazine grinder possible. Many other improvements not specifically discussed above will be described in the Vfollowing detailed description and claimed in the appended claims.

Afpreferred embodiment of my invention is illustrated in the accompanying drawings, a study of which will make clear the prin-` ,practically constant, the grinding action is i neemt/er ciples involved.. In these drawings Fig. i.

and 1 taken together constitute an elevation of the complete inder showing the magazine, the feed chains, the driving units. and the feed control mechanism; F1g. 2 is a view of the grinder looking at thedriving or motor side; Fi 3 is a vertical section of the grinder looking from the driving or motor end and showing the relation o? the various parts of the magazine to those of the grinder frame, particularly the provision made for centering the magazine over the grindstone as well as for stopping the escape of steam into the atmosphere of the rinder room, together with an-arrangement or circulating the stock in the pit below the grindstone; Fig. 4 is a vertical section taken through the center line of the grinder arallel to the main shaft, showin the steel linger plates on the magazine an -a water cooling arrangement located on the shaft between the housing and the bearings, as well as a method of circulating the stock inthe pit below the grindstone; Fig. 5 is a lar e scale section. showing the chain leaving t e wood at the bottom sprocket and the spurs in the chain being withdrawn from the Wood in the direction of their length, together with the allowance provided tor, due to the decrease in the diameter of the grindstone; Figs. 6, 7 and 8 are large scale views showin the relation oit the various parts of the c ain to one another, the special track and the manner in which the chain rollsdown the inside of the chain guide on the track in the magazine; Fig. 9 is a large scale section of one of the water jackets around the grindstone shaft showing the relation of the grindstone, concave stone flange, sole plate and bearing relative to the water jacket; Fig. 10 is a arge scale section of the concaverstone iange showing a self-centering brass interior bushing so arranged that the flange Will tit a grindstone having non-parallel sides; Fig. 11 is a wiring diagram showing the vconnections of the principal electrical parts shown in Figs. l ad 1; Fig. l2 is an elevation of a modied form of grinder looking on the motor side showing the combination of chains used for packing and feedi'n the wood in the magazine against the grlndstone; and Fi 13 is an elevation of the form shown in ig. l2 viewed parallel to the grinder shaft.

The magazine grinder shown in Figs. l to 9 inclusive comprises an, ordinary cylindrical grindstone 21, enclosed'within housing 24, mounted on shaft 22, journaled in water cooled bearings 23. anddriven by aA synchronous motor 59. The stone is securely fixed upon the shaft by means ot bushings 25, :and concave steel stone flanges 26, designed to hold it central on the shaft, even thou h cracked. Below 'the grindstone is a pit 2 one end of which forms a dam 28, or

overow of variable height to keep the bottom of the stone immersed in stock to any required depth and over which the ground Wood pulp passes. Adjustably mounted on the housing 24, and located centrally over the grindstone is a vertical magazine 29, into the upper end of which is placed the wood to be ground.

A positive and continuous, though variable t'eed of wood in this magazine is secured by means of four endless thimble roller chains 30, two located on each of the two opposite sides of the magazine parallel with the shaft 22, and which roll down the inside ofthe magazine on specially prepared tracks 31, in chain guides 32, securely fastened to the magazine. A vertical slot 33, is cut in the web of each of thefour guides and in the shell corres onding to Where these slots come in the gui es near the upper end of the magazine, to allow the chains 30, toenter the magazine and haul the wood against the grindstone. Likewise slots 34, are cut in the webs of each of the Jfour guides and in the shell-correspondingto where these slots come in the guides near the lower end of the magazine, to allow the chains to pass out ot' the magazine. The remainder of the inside of the magazine is lined with heavy planking (not shown). 'llo prevent-bulglng of the magazine on account ofthe excessive internal pressure set up (due to the pressure exerted by the chains on the wood), beams 35 are riveted to the exterior ot the magazine at intervals.

These feed chains 30 are unusually strong as they must exert a working pressure of approximately 64,000 pounds between the wood in the magazine and the grindstone. Each chain is made up ot' one continuous length having many sections or pitches of exactly the saine distance between centers of ins (see Figs. 6. 7 and 8). Each pitch ength of the type oit' feed chain 30, shown in Figs. 6, 'i' and 8, is made up ot two side links 44 and 74; one thimble 45: one roller 46; one pin 4T; six spurs, two each of 48, 49 and 50; and a special oiling feature 51, located in the head end otl cach pin 47, for lubrication of the chain. These chains are ot special construction, side links 74 are breached for lhilnble 45, so there may be no turning ot 74 on 45, side links` 44 are breached for one head o1 pin 4T. in this head of the pin is located the special oiling feature for lubricating the chain by means of a pressure gun. The holes for thimble 45 and pin 47 are not located centrally in links 44 or 74,'so that the roller 46 will project beyond the back of the side links 44 or 74, transmit the pressure to the tracks 3l, and roll down the inside of the chain guides 32, on tracks 3l. On the face of the chain against which the wood presses the links pro- A ject beyond the race of the rollers a distance great enough to insure against the pressure forcing the wood against the face of the roller 46. If the wood presses against the rollers the chains will slide rather than roll down the tracks 31, and encourage spots on the rollers thereby weakening the chain, and increasing the power consumption. In the forward end of each link just ahead of the thimble is located one long spur or spike 48, following this is'a spike of intermediate length 49 and inthe center of each link is a short spike 50, the functions of which are to impale or spike the blocks of wood and force them downward against the grinding element. The position of the spikes in the links is all important; if they are not located toward the forward ends of the links they will tear a piece out of the block of. wood as the chains move around the lower sprockets and away from the magazine, thus increasing the power consumption and doing considerable damageto t e chains as well as increasing the amount of slivers. With the correct arrangement of these spurs the chain moves away from the ywood around the lower sprockets as shown in Fig. 5, and, the links being in effect pivoted at their upper ends, the spurs are withdrawn from the wood in the direction of their length as a nail is drawn from a board, with ease and without tearing or ripping the wood.

The magazine is slightly larger at the top than in its main body. The purpose of this tapering of the top of magazine is gradu ally but surely to force the spikes into the blocks of wood and to compact the blocks intoa solid mass so the chains will effectively hold the wood to be ground. For this purpose it has been foundl desirable to make lthe to of the magazine about (1) wider than tie main body of the magazine. This taper should gradually decrease until about one-third the way down the magazine when it maintains a normal-or constant width,-

until the magazine again tapers outwardly below the lower sprocket.

The feed chains 30 are driven by sprockets 39 mounted upon the lower end of the magazine and very close to the grindstone. As shown, the chains as they pass around these sprockets and the grindstone itself are substantially tangent to the same horizontal plane. As a matter of actual measurement, l have found that` the distance between the top of the stone and the point where the chains leave the wood should be about 9 inches although it ma be somewhat more than this and still avold binding and counter-arching. llt may also, of course, be less than this.

The sprockets 39 are driven by a variable speed feed motor 52, through the speed reducing transformer 53, worm gear 54, and

worm gears 55. This drive is mounted on a frame 36, which is rigidly secured to the magazine 29. When the chains leave the lower sprockets they pass 'out of the housings through openings 56, ascend the out; s1

e of ythe magazine and are engaged by idler sprockets 38, over which thie chains are carried and passed through the openings 33, in the upper end of the magazine to engage the wood and force it downward against the grindstone, These idler s rockets are journaled in bearin 42, rai by yokes 41 and vertically slida le on guides 43. By turning screws 40 supported upon brackets 101 the yoke 4l and bearing 42 can be raised to increase the distance between the centers of sprockets 38 and 39 and take up any slack in the chains. Guards 57 protect the workman on the charging ioor against injury through coming in contact with the chains.

The grindstone is driven by synchronous motor 59, On the same shaft is mounted a. direct current generator 60 driven by the motor 59, which excites the ieil of the latter and supplies power to the variable speed motor 52 during the time the synchronousv motor is operating. Before starting the synchronous motor, however, it is necessary to reverse the variable speed feed motor 52, to release the pressure between the grind stone 4and the wood which would otherwise act as a brake. To do this a motor generator set 61, is installed to provide power to the variable speed feed motor when reversing.

Automatic regulation of the speed of the feed chains with reference to the power consumption of the synchronous motor driving the grindstone is obtained in the following Way: Current i's delivered to the synchronous motor 59, from the three main feeder lines; a torque motor 63 is connected in parallel with the motor 59, through a current transformer 62, so that the current transmitted to it is proportional to the current transmitted to the synchronous motor 59. vThe shaft of the torque motor is connetted to the movable contact arm 64 of a vrheostat 58, which controls the resistance in the field ofthe feed chain motor 52 and thus controls the current in the field and the speed of the moto-r. At full load the torque in the induction motor is balanced by a weight 65. If the load on the synchronous motor 59 drops off, the torque of the induction moto-r is decreased; the weight 65 overcomes the torque and produces rotation of theV induction motor 63, This rotation of the induction motor 63 moves the rheostat arm across the face of the rheostat 58. and inserts additional resistances in the field circuit of the variable speed feed motor, which causes this motor to speed up. This results in increasing the load on the synchronous motor 4producing a balanced system. Conversely if the load on the synchronous motor asomar increases, the torque of .the induction :motor is increased; the torque overcomes the weight and produces rotation or" the torque motor vin .the opposite direction, which moves the rheostat arm across the face of the rheostat and displaces. resistance in the ield circuit of the Variable speed feed mot/or causing the s d of this motor to decrease. This results in decreasin' the load ou the synchronous motor, pro ucing a balanced condition. If the wood were always led at a constant rate against the grindstone, then,

when grinding small, sot or loosely packed Ablocks of wood, the power consumption wood at a practically constant power con- .sumption of the grindstone by varying the feed of the wood Uainst the grindstone. l

ln connection wit this electrical arrangement for controllin the feed ci the wood in the magazine l esire it -to be ully understoodtnat l am quite aware of certain electrical devices for controllinw the Jleed of certain machines such as United States Patent 1,070,638,1'dated Aug. 19, 1913, granted to L. H. Thullen of Cincinnati, U., as well as to others for the purpose or' automatically controlling electric motors driving iced carriages for friction or other saws. ln my invention l make use of a did'erent though somewhat similar arrangement of electrical control and apply my arrangement oi electrical `control to the operation of a magazine wood pul Y grinder- The electrical contro-l of itself, do not claim, but l do claim the use of such control in conjunction with magazine grinders for grinding wood pulp lt is common practice to supply the water necessary for grinding wood at the ace ot the grindstone with the attendant dangers previousl disclosed. ln this invention, water is introduced at the upper end oi the magazine through pipe 66, and sprayed over the wood in the upper part of the magazine. This Water trckles down over the blocks in the magazine, absorbs the hot water vapor rising from the grinding surface, becomes hot and a percentage reaches the grindstone in the form of hot water. The percentage of water entering the top ci the magazine that does not reach the grindstone in the form of hot water is'absorbed by the blocks of wood in the magazine which become softened before reaching the grinding element. This contact of water and hot water vapor has not only resulted in preheatf ing the water reaching the grindstone 'as well as softening the wood in the magazine, but the vapor risin from the grindstone is eliminated. The e oiencies derived from introducing water at the top of the magazine are very important. The benefits ma be reviewed as follows, first, the water 1s preheated before coming in contact with the grindstone, thus minimizing the danger of craclrino or shelling; second, the wood is thorougllly softened before grinding and consumes a minimum of power; the sensible heat otherwise lost or requiring means for removing the same is conserved and used..l

ln order to compensate for the wear ol the grindstone, the magazine is constructed to allow off vertical adjustment. Magazine 29 is supported on the housings 75 and 76, by means oi adjusting screws 67 and 68, that pass through the brackets 69 and trame 36, which are securely riveted to thema azine. Each adfusting screw is provi* ed with three nuts l0, which when properly set and tightened hold the magazine adjacent to the grindstcne. To locate the magazine centrally above the orindstone no matter whether the size ol this grindstone be manimum or minimum, Aalso to prevent 'passage of steam 'from the inside oi the housing into the atmosphere oi the grinder room, the magazine is provided with two angle seals ll, and two plate seals l2, which are a part oi' the magazine and are machined smooth and square, thus locating the magazine centrally on the grindstone as well as providing a perfect seal against the escape of the steam within the housing.

ln order to taire care of this great pressure existing within the lower end of the magazine, l provide cast steel linger plates 77 riveted on the inside of the magazine and heavy cast steel angle seals il riveted on the outside continuing the entire distance aerox the magazine. The whole may now be considered a built up beam ol enormous strength. To oppose the pressure of this beam and to taire the pressure exerted on this by the force ci the grinding action there is incorporated in the grinder end 78 another yery heavy beam which provides the bearing or track for this improved foot of the magazine to slide upon, and transmits the thrust to the grinder frame. This sliding referred to is necessary because the diameter oi the grindstone constantly decreases due to wear and the magazine must be lowered. On account or the corrugated shape ot the lower edge of these finger plates the ground wood can escape from the magazine into the pit 9.7 below. If for any reason these apertures become blocked there is a clearance provided at the bottom of the magazine on the two ends on which the chains do not operate where the ground wood can flow out of the magazine over the concave steel .flanges holding the grindstone andA into the pit below.

' metal with which these rings are line I have provided means for cooling the shaft between the housing and the bearings- 23. This ap aratus comprises a pair of water cooling jackets 37, throu h which water is forced under pressure. e water jackets are assembled in four pieces around the shaft and are bolted to the housings 75 and 76. Packing is provided at both ends of the water jackets to prevent the leakage of water between the shaft and the jacket. Water is introduced at the top of these jackets, flows around the shaft 22, and away through an opening in the bottom of the water jackets. In the above manner, the heat conducted from the lgrindstone along the shaft is absorbed by t e cooling water and carried oi, thus eliminating a serious source of trouble in the bearings. y

Bearings 23 are of special design and are arranged so that a constant flow of water is circulated within the bearing to-assist in keeping the bearing metal cool. To lubricate the shaft in this bearing, oil is supplied to the shaft from a special spray pipe 89. Should lateral adjustment of the bearing be necessary this may be accomplished by means of set screws. To provide for vertical adjustment wedges 90 may be moved toward or away from one another by :means of set screws mentioned above'. l

To support the magazine and provide a covering for the grindstone, also to take the thrust from the magazine due to grinding, a substantial housing consisting of grlnder sides 75 and 76, grinder ends 78 vand 79, and sole plates 80 -is provided.

Within this housing and located in front of the grindstone is a swinging dashboard 81, provided with a toothed design on its lower edge. The function of this 1s to keep the cold spray water fed to the pulp in the pit from striking the grindstone directly, as well as to give an equal distribution of the water sprayed on the upper part of the fiashboard by the spray from the spray pipe 82, and descending into the pit 27. A doorV 83 is provided in grinder side 76, farthest from the synchronous motor, to permit removing the wood in the ma azine when required. In grinder ends 8 and 79 are special slots 84 to rovide space for the sprockets 39 and cham 30, when the magazine reaches its lowest position. To inspect quickly the operation of the grindstone or that part of the grinder Within the housing, peep-holes 102 are located in the grinder ends 78 and 79. Should it become necessary to change the 'grindstone or make repairs inthe pit, the entire magazine and hydraulic stone truin lathe 85 1s provi ed and lsupported on e inside of the sole plates 80. v.To allow for ease of operation and so the workman will not have to get his arm inside the grinder housing when sharpening the stone, this stone truing lathe is made to project through openings in each ofthe sole plates 80, thus allowing the carria run out o the housing at any time. When necessary to follow the carriage across the face ofthe indstone a narrow door 86 is provided, t e bottom of the opening between the sole lates is covered by two sliding doors 87. o permit of sharpening the indstone when 1t has been reduced in iameter and it is no longer possible to run the carriage holding the burr against the grindstone, a bracket 88 on the inside of each sole plate allows for the stone truing lathe being advanced as required.

Located in the pit with the stock is an agitator 91 to prevent the accumulation of slivers or heavy stock. Slivers will burn the face of the indstone and destroy its cutting surface i allowed to rub against it for a period of time. The accumulation of heavy stock in any one place in the pit will cause the water in the stock to leave the same and run away in channels in the pulp, thus ermitting the grindstone to become very het with the possibility of frac` turing.

on thestone truing lathe to be The method of o eratin the apparatusy previously describe may e reviewed as follows. 'Magazine 29 is filled with pulp wood lying parallel to the face of the grindstone, water is sprayed on this wood through a supply pipe 66, situated at the up er end of the magazine and continuous feed) chains of heavy design containing spurs as shown after repeated o servations that when the` sprockets are located a considerable distance up the magazine binding caused by counterarching within the lower end of the magazineis set up, the wood is not fed down the magazine at a constant rate, excessive strains are put on the various members and the power consumption is not constant over a ocks of period of time. When the sprockets. are placed in their extreme low position counter-arching ceases, the wood moves down the magazine'in the form 03E a continuous column, thepressure lines pointing downward ,and toward the centre 'so as to form a cone having its apen pointing downward. When such a condition is obtained, the apex of every cone formed is being continuously. round oh; then, and then only, can wood e ground in the form of a continuous column. The lower end of the magazine from about the centerx line of the bottom sprocket to that edge which is adjacent to the face ci the grindstone, is tapered to a slightly larger size than the section at, and above the sprockets 39, this so as lto reduce binding kand arching in the section below where the spurs are withdrawn from the wood. .lt so happens when dry wood'i's being ground, that the swelling in this section due vto steaming of the wood will be considerable and cause binding which is overcome by slightly tapering the lower part of the magazine. rEhe pulp after being ground in the magazine is carried through openings in the linger plate 77 by the revolving grindstone and is deosited in the pit 27, where .it is circulated by agitator 91, flows over the inclined dam 28 and is carried away to the screens. The lower part of the stone is always rotating in a pulp bath. s the upwardly moving face of the stone emerges from this bath the pulp rolls 'from it in such a manner as to clean it and permit its return to the wood in excellent condition. W hen this action is disturbed the stone is slimed over and an excess of ower is consumed before the stone settles own to normal grinding again.

Fitting the concave langes to the grindstone is dilicult if the sides of the stone be notparallel. I overcome this diiculty by providing a self-centering bushing 93, having a curved exterior which allowsv of a slight movement of the concave steel stone flange 26v on the spherical surface of the brass bushing 93. (See Fig. 10).

In order to deliver the wood to the feed chains in the form of a compact massa set of packing chains may be employed as shownl in the modiiied form of grinder shown in Figs. 12 and 13. These packing chains 94 are"0 erated in a similar manner to that in which the single set oi' feed chains are operated. Frame 95 is rigidly attached to the magazine and supports the driving arrangementas well as the reduction gearing for this drive. The packing chains are driven by a variable speed motor 96. Current is' supplied to this motor by means of a motor generator set (not shown). This current passes through. a

current regulator, as, for example, a Brush regulator, 'placed in the line between the motor generator and the motor 96, thus only a definite power or torque can be delivered at Ia given voltage. For example, if the wood being fed by the chains 30 decreases in velocity down the magazine then theY pressure between the wood held by the packing chain-s 94 and the wood held by the jure the motor or cause burning, because the current'regulator controls the amount' of current going to the motor 96 and there can neyer be more than a predetermined amount of torque on this motor. s already described a given amount of ower is always delivered to the motor 96 which can only overcome a certain pressure. When the resistance to the motor decreases the motor will start up ii the motor is stalled, orif the motor has only slowed down the revolutions will increase to give the required pressure between the two bodies of wood in the magazine. The speed reducing arrangement for operating the packing chains 94 is obtained by means ot1 spur gear reducer 97, worm gear reducer 98, and worm gears 99. The feed chains in this instance are operated in exactly' the same manner and with exactly the same reducing gearing as thatpreviously described for operating the `leed chains in Figs. 1 to 6. The arrangement described above is shown in Figs. 12 and 13 of the accompanying draw-ings.

The complete apparatus as described permits of grinding wood continuously without an interruption even when the grindstone is being sharpened, and with a substantially constant power consumption of the grindstone.

Cross-reference is hereby made to the following copending applications: Serial No. 696,781, filed March 4, 1924; Serial No. 096,782, tiled March 4, 1924;and Serial No. 703,348, tiled April 1, 1924.

1. A wood-pulp grinder of the magazine type comprising the combination ot' a grindstone, a magazine of substantial height in comparison with the diameter of the grindstone, mounted above the grindstone, endless feed chains designed to move in a plane parallel to the plane of* rotation of the grindstone along substantially the entire length of the magazine, means carried by the chains to positively grip the wood along its sides and continuously force it against the rindstone, and drivi sprockets for the c ains situated so close y. adjacent the rindstone that the wood cannot arch or jam-in the lower end of the r magazine.

2. A wood-pulp grinder of the magazine type comprising the combination of al indstone, a magazine adjacent the grin stone and adapted to receive the wood to be ground, endless feed chains o erating in the magazine for positively fe ing the vwood to the grindstone, a variable speed motor driving the feed chains, and means for varying the speed of the motor relative'to the power consumption of the grindst-one.

3. A Wood-pulp grinder of the magazine type comprising the combination of a indstone, a magazine adjacent the grin stone ada ted to receive the wood to be ground,

fee ing means for gripping the wood andc'ontinuously forcing it -against the grindstone, designed to travel with the Wood along those "sides of the magazine which, if extended, would intersect the cutting face of the grindstone, the-point where the wood leaves the feedin means being so closely adjacent the grin stoine that the wood cannot arch or jam in l,the lowerend of the magazine.

4. A Wood-pulp grinder of the magazine type, comprising the combination of a grind stone, a magazine adjacent to the grindstone and adapted to receive the wood to be ground, endl/ess feed chains operating in the magazine for positively feeding the wood to the grindstone, a variable speed motor driving theI feed chains, a rheostat controlling the current through the field of the variable speed motor, and means responsive to the power consumptioni' of the grindstone operating the rheostat and thus controlling the speed of the feed motor.

5. A wood-pulp grinder of the magazine type, comprising the combination of a grindstone, a synchronous motor driving the grindstone, a current transformer in the line feeding the synchronous motor, a magazine adjacent to the grindstone and adapted to receive the wood to be ground, endless feed chains operating in the magazine for positively feeding the Wood to the grindstone, a variable speed motor drivin the feed chains, a'rheostat controlling t e current through the field of the variable speed motor, a torque motor in parallel with the synchronous motor through the current transformer operating the rheostat to throw in more resistance as the power consumed by the synchronous motor decreases, and

vice versa, thus causing the speed of the feed motor to vary inversely with the power consumption of the synchronous motor.

6. In a Wood-pulp grinder of the magathe spurs are withdrawn from the wood substantially in the direction of their length.

8. A Wood-pulp grinder of the magazine type comprising the combination of a grindstone, a" ma azine adjacent to the grindstone and a apted to receive the wood to be round, and endless feed chains equipped wit wood-gripping spurs operating in the magazine for positive y feeding the wood to the grindstone, and driving sprockets for the chains'situated at thelower end of the magazine, the driving s rockets andl the grindstone being substantiall tangent to the same horizontal plane, an the axes of rotation of the drivin sprocket and the .grindstonev bein parallel 9. A wood-pu p grinder of the magazine type comprising the combination of a grindstone, a ma azine adjacent to the grindstone and a apted to receive the wood to be ground, and endless feed chains operating in the ma azine for positively feeding the wood to t e grindstone, trackways for the chains on the inner face of the magazine, and anti-friction rollers on the chains contactin with the trackways.

l0. n a Wood-pulp grinder of the magazine type, the combination of linked feeder chains operating within the magazine, antifriction rollers on the chains preventing contact of the links With the magazine walls, and means for lubricating the chains.

l1. In a wood-pulp grinder of the mavazine type, the combination of linked fee er chains operating within thevmagazine, antifriction rollers on the chains preventing contact of the links with the magazine walls, and means protecting the rollers from the Wood in the magazine so that they shall be free to rotate.

12. In a Wood-pulp grinder of the ma azine type, the combination of linked fee er chains operating within the magazine and a series of Wood-gripping spurs of graduated lengths on the links, the longest spurs being nearest the forward ends of the links.

13. In a wood-pulp grinder of the magazine type, the combination of linked feeder chains operating inside the magazine, all the links being equipped with wood-grip- ,the chain turns about the lower sprockets ping spurs near .forward ends, and continumg to the center ofl each link, all ahead of the' rear pin onV which the link fulcrums.

14. A wood-pulp grinder of the m zine type, comprisin thceo'mbination o a grindstone, a magazine adjacent the grindstone for receiving the wood to be ground, endless feed chains operating in the magazine for positively feeding the wood to be ground to the glrindstone, and se rate packing chains in t e upper end of e magazine for feeding'the wood to the feed chains in compact form.

15. A wood-pnl grinder of the magazine type, comprising the combination of a rindstone, a magazine adjacent the grin stone Y for receiving the wood to be ground, endess feed chains o ing in the magazine for sitivel feeding the wood to .be ground tot e grin stone, vseparate packin chainsA in the upper end of the magazine or lfeeding the wood to the feed chains 1n compact form 'and a variable speed motor driving said packing chains, the speed of said motor varying inversely with the pressure exerted by the packing chains. c l

16. A wood-pnl grinder of the magazine type, comprising t e combination of a grindstone, a magazine adjacent the grin stone for receiving the wood to be round, endless feed chains operating in t e magazine C' for sitivel feeding the wood to be ground tothg grindstone, separate packin chains in the upper end of the magazine or feeding the lwood to the feed chains in compact form and a variable speed motor Ydriving said packing chains, designed to cease o erating whenthe pressure exceeds a pr etermined maximum.

17. In a wood-pulp grinder of the magazine type the combinationlof a grindstone, a magazine for `holding the wood to be ground, a linked feeder chain operating with- 1n the magazine *to feed the wood downwardly, a sprocket near the base of the magazine about which the chain turns, woodgripping spurs near the forward ends of the chain links so designed that when the chain turns about the lower sprockets the s urs are withdrawn from the wood substantially in the direction of their length, pockets'in the grinder ends for the purpose of containin the sprockets as the stone wears away an the magazine is lowered.

18. A wood-pulp grinder of the magazine type, comprising the combination of a grindstone, a housing therefor, a magazine mount: ed upon the housing for receiving the wood to be ground, means for adjusting the position of the magazine relative to the grindstone so that as the stone wears the spacingof the lower end of the magazine relative to the inding surface can be held constant, vertical trackways on the inner face of the housing and means for supporting tively feeding the wood to the motor mountedu n the magazine for driv- 'combination o thelo'wer end of the magazine against the trackways in all positions of the magazine.

19. A wood-pulp1 grinder of the magazine type, comprising t e combination of a grindstone, a ma jacent to said grindstone and adapted to receive the wood to be ground, and endless chains operating the entire length of the magazine to force the wood against the grindstone, the said magazine being sli htly larger at the top when in the niain ody of the magazine where it maintains a'. normal or constant width until the m zine tapers outwardly n ear the lower sproc et.'

20. A wood-pnl' grinder of the mazazine gazine situated centrally and ad-` type, comprising t e combination of a rind- Y stone, a m zine adjacent the grin stone and adapte to receive the wood to be ground, endless feed chains operatingv in the magazine and .mounted thereon for posi- 'ndstone a ing the feed chains, and means for adjustj ing the position of the magazine relative to the grindstone se that as .the vstone wears the relation of the magazine and the feed chains to the grinding surface can be held constant.

21. A timid-pulp1 grinder of the magazine type, comprising t e combination of a grindstone, a magazine adjacent thereto receiving the wood to be ground, endless feed chains operating in the magazine for itivel feeding the 'wood to the grindstoilig uppesi" and lower s rocket wheels mounted upon the magazine a ut which the feed chains travel, drivin means mounted upon the magazine for drivin the lower sprockets, and means whereby e entire magazine with its feed chains, sprockets andA driving vmechanism can be moved bodily toward and away from the grindstone so that as the stone wearsthe relative position of the parte shall remain unchanged.

22. A woo ulp grinder comprising the a grindstone, a magazine adjacent the grindstone adapted to receive the wood to be ground, means continuously operating along those sides of the magazine which, if extended, would intersect the face of the grindstone for gripping the wood and forcibly feeding it against the indstone, and means for increasing the liseral pressure on the wood in the interior of the charge to compact it as it approaches the grindstone.

23. A wood-pulp grinder comprising the combination of a grindstone, a magazine adjacent, the grindstone adapted to receive the weed to be ground, the width of the magazine decreasing toward the grindstone, and oppositely disposed feed chains within the magazine for forcing the wood against the grindstone.

24. A wood-pulp grinder of4 the magazine type, comprising the combination of a grindstone, a housing therefor, a magazine mounted upon the housing for receivin the wood to be ground, means for orcin t e wood in the magazine a einst the grin stone, means for adjustin t e position of the magazine relative to te grindstone so that as the stone wears the spacing of the lower end oi the magazine relative to the! inding surface can he heid constant, an reenrorcing means on the housing'and the iower end the magazine cooperating to'l sustain the grinding pressure in all positions oi the magazine.

25.. A wood-pnl grinder of the magazine type, comprising tiie combination oi? a grindstone, a housing thereior, a magazine mounted-upon the housing for receiving the wood to be ground, means for forcing the wood in the magazine against the grindstone,and a reenforcing beaml extending across the lower end of the magazine cooperating with the housing to sustain the grinding pressure in all positions of the magazine.

26. A' wood-pul grinder of the magazine type comprising t e combination of a grindstone, a magazineof substantial height in comparison with the diameter of the grindstone, mounted above the grindstone, endless wood-grip ing feed chains operating along substantia ly the entire length of the magazine to grip the wood along its sides and continuously -force it against the grindstone, and driving sprockets for the chains situated near the lower end.of the ma azine, the width of the magazine being s ightly greater adjacent the grindstone than at the point where the driving sprockets are mounted.

27. A wood-pui grinder of the magazine type, comprising t e combination of a grindstone, a synchronous motor driving the grindstone, a magazine adjacent to the grindstone and adapted to receive the wood to he ground, endless feed chains operating in the magazine `for positively Vefedii'ig the wood to the grindstone, a variable speed motor driving the feed chains, a rheostat controllin the current through the iield oi the varia le speed motor, a torque motor in parallel with the synchronous motor operating the rheostat to throw in more resistance as the power consumed by the synchronous motor decreases, and vice versa, thus causing the speedl of the feed motor to va inversely with the power consumption o the s nchronous motor.

28. A wo -pulp grinder of the magazine type, comprising the combination of a grindstone, a magazine' adjacent thereto receiving the wood to be ground, feed chains mounted upon and carried by the magazine for positively forcing the wood against the grindstone, driving sprockets for thefeed chains mounted upon the magazine adjacent the grindstone, and means for adjustin the position of the magazine relative to t e rindstone so that as the stone wears the re ation of the driving sprockets to the grinding surrace can be held constant.

29. A wood-pulp grinder of the magazine type, comprising the combination of a grindstone, a magazine situated adjacent to said grindstone and 'adapted to receive the wood to be ground, wood-feeding means supported upon the magazine and operating along those sides of the ma azine which if extended would intersect t e cutting face of the grindstone enga ing the sides of the charge for forcibly feeding it to the grindstone, and operating for substantially the entire length of the magazine, the point where the wood leaves the feeding means being so closely adjacent the grindstone that the wood cannot arch or jam in the lower end of the magezine, and means for adjustin of the magazine relative to the grindstone so that as the grindstone wears away the relation between the feedin means and the grinding surface can be he d constant.

30. A wood-pulp grinder of the magazine type comprising the combination of a rindstone, a magazine adjacent the grin stone adapted to receive the wood to be ground, feeding means operating along the sides of the magazine fory continuously forcing the vwood against the rindstone, the point where the wood leaves t e feeding means being so closely adjacent the grindstone that the wood cannot arch or jam in the lower end of the magazine, and reenforcing means on those sides of the magazine along which the feeding means operate and between the oint where the feedin means leave the woo and the stone, to wit stand the outward thrust orI the Wood.

31. A wood-pulp grinder of the magazine the position type comprising the combination of a ffrindstone, a magazine adjacent to the grindstone and adapted to receive the wood to be endless feed chains operating in the magazine for positively feeding the wood to the grindstone, driving sprockets for the chains situated at the lower end of the ma azine, 'the driving sprockets and the grindstone being substantially tangent to the same horizontal lane, and re-enforcing means between the riving sprockets and the grindstone for withstanding the outward thrust of the wood.

32. A wood-pulp grinder of the magazine type comprising the combination of a rindstone, a magazine adjacent the grindstone ada ted to receive the wood to be ground, fee chains equipped with wood gripping and penetrating means for continuously forcing the wood against the grindstone designed to travel with the wood along those sides of the magazine which, if extended, would intersect the cutting face of the grindstone, and driving sprockets for the chains situated so' ,closely adjacent the grindstone that the wood cannot arch or jam 1n the lower 'end of the m zine.

3.3. A wood-pu p grinder comprising the combination of a grindstone, a magazine adjacent the grindstone adapted to receive the wood tobe ground,- the width of the' magazine decreasing toward the grindstone, and oppositely disposed wood feeding means designed to operate continuously along those sides of the magazine which, if extended,

would intersect'the face of the grindstone for grippin the wood and forcibly feeding it againstt e grindstone.

34. A wood-pulp grinder ofthe magazine type comprising the combination of a stone, a ma azlne `adjacent the grin stone and adapte to receive the wood to be ground, wood feedingmeans operatin alon the sides of the magazine for itive y an continuously feeding the w to the grindstone, a variable speed of the motor relative to the power con- J. J. WAR EN.

ind-

(sipeed motordriving the feeding means, anmeans forvarying the- 

